A group of researchers coordinated by MIT (Massachusetts Institute of Technology) published in the journal “Nature” the results of the most sophisticated simulation of the universe ever produced. It’s Illustris, a project that led to the creation of a model to faithfully reproduce the evolution of the universe from 12 million years after the Big Bang to the present day.
The project Illustris took five years just to develop the software needed to create such a sophisticated simulation. In the past, similar attempts were practically impossible because of the limitations of the hardware existing until very recently. Today it’s been possible to use various supercomputers with a total of 8,000 CPUs: Ranger and Stampede and the Texas Advanced Computing Center, the French CURIE at CEA and and the German SuperMUC at the Leibniz Computing Centre.
Despite this computing power distributed among different data centers, the researchers took three months to build the model. It consists of a cube of 350 million years of light long on each side and at the end contained 41,416 galaxies of various types that mirror the distribution existing in the physical universe.
The consistency of the results confirms the findings of modern astrophysics. The researchers reproduced a wide range of observable properties of galaxies and the relationship between these properties. They precisely measured the amount of gas in the universe and its position. They were able to investigate the number of “satellite” galaxies, their properties and their connection with cosmology. They can study the changes in the internal structure with the evolution of the galaxies. They can study the impact of gas on the structure of dark matter. They can make virtual observations to analyze the properties of the model.
The physical observations of stars and especially galaxies offer us a window into the past. The virtual universe of Illustris allows to examine the whole or part of the history of a galaxy or a cluster of galaxies going back and forth in the virtual time. Simulations of this kind will also allow much more detailed comparisons between the virtual and physical observations to understand where the current theories have yet to be refined.
In fact, the Illustris simulation isn’t 100% faithful. For example, it’s been observed the formation of virtual small galaxies sooner than it’s been observed in the physical universe. This is important because we know that there are still mysteries in the universe, starting with the problem of dark matter and dark energy. Creating sophisticated simulations will allow to check more simply new versions of the astrophysical theories giving scientists the opportunity to improve our knowledge of the universe.